首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   94002篇
  免费   1229篇
  国内免费   433篇
电工技术   988篇
综合类   2322篇
化学工业   12814篇
金属工艺   4961篇
机械仪表   3284篇
建筑科学   2571篇
矿业工程   625篇
能源动力   1343篇
轻工业   4490篇
水利工程   1350篇
石油天然气   373篇
武器工业   2篇
无线电   10248篇
一般工业技术   17858篇
冶金工业   5416篇
原子能技术   351篇
自动化技术   26668篇
  2021年   94篇
  2020年   66篇
  2019年   101篇
  2018年   14593篇
  2017年   13485篇
  2016年   10066篇
  2015年   719篇
  2014年   407篇
  2013年   727篇
  2012年   3471篇
  2011年   9743篇
  2010年   8664篇
  2009年   5934篇
  2008年   7195篇
  2007年   8111篇
  2006年   474篇
  2005年   1569篇
  2004年   1361篇
  2003年   1446篇
  2002年   799篇
  2001年   292篇
  2000年   396篇
  1999年   256篇
  1998年   753篇
  1997年   554篇
  1996年   420篇
  1995年   314篇
  1994年   265篇
  1993年   275篇
  1992年   141篇
  1991年   140篇
  1990年   135篇
  1989年   139篇
  1988年   136篇
  1987年   96篇
  1986年   93篇
  1985年   116篇
  1984年   123篇
  1983年   100篇
  1982年   79篇
  1981年   82篇
  1980年   91篇
  1979年   85篇
  1978年   93篇
  1977年   127篇
  1976年   212篇
  1974年   65篇
  1968年   66篇
  1955年   71篇
  1954年   69篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Mobile software applications have to cope with a particular environment that involves small size, limited resources, high autonomy requirements, competitive business models and many other challenges. To provide development guidelines that respond to these needs, several practices have been introduced; however, it is not clear how these guidelines may contribute to solve the issues present in the mobile domain. Furthermore, the rapid evolution of the mobile ecosystem challenges many of the premises upon which the proposed practices were designed. In this paper, we present a survey of the literature on software assurance practices for mobile applications, with the objective of describing them and assessing their contribution and success. We identified, organized and reviewed a body of research that spans in three levels: software development processes, software product assurance practices, and software implementation practices. By carrying out this literature survey, we reviewed the different approaches that researchers on Software Engineering have provided to address the needs that raise in the mobile software development arena. Moreover, we review the evolution of these practices, identifying how the constant changes and modernization of the mobile execution environment has impacted the methods proposed in the literature. Finally, we introduced discussion on the application of these practices in a real productive setting, opening an area for further research that may determine if practitioners have followed the proposed assurance paradigms.  相似文献   
3.
This paper presents an integrated passive damping approach in hybrid metal-CFRP parts for structural applications. In this concept a viscoelastic material is embedded in the joint zone of the hybrid component. To examine the connection strength single-lap-joint specimens were produced and tested and the influence of the used material combinations, different surface structures, and different process parameters i.e. the moment of cross-linking were evaluated. Afterwards, the metal-CFRP hybrids were tested in quasi-static tests to assess their connection strength and failure behaviour. Dynamic cyclic tensile tests with step-wise increased loading conditions were performed to determine the specimens damping behaviour and to estimate their fatigue performance. Finally, these results are compared to a state of the art metal-CFRP hybrid with rivets connecting both materials.  相似文献   
4.
In this paper, we consider the classical finite mixture model, which is an effective tool for modeling lifetime distributions for random samples from heterogeneous populations. We discuss new results on stochastic comparison for two finite mixtures when each of them is drawn from one of the following semiparametric families, i.e., proportional hazards, accelerated lifetime and proportional reversed hazards.  相似文献   
5.
6.
7.
Variations of Incomplete Open Cubes is the major project by the twentieth-century conceptual artist Sol LeWitt. In this paper we interpret the enumerative component of the project as embeddings of graphs. This formulation permits use of an algorithm to check the completeness of the list of the structures produced by the artist. Our conclusion is that the artist found the correct number of structures (that is, 122), but that his list contains a mistake in the presentation of a pair of incomplete cubes, a discovery that appears not to have been noted before.  相似文献   
8.
9.
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号